Upon cold start of a motor vehicle, there is an amount of time in which components such as exhaust gas constituent sensors warm up to their respective operating temperatures (e.g, light-off time). During this time, a sensor signal may be unstable and the sensor measurements may be inaccurate. In particular, while manufacturing processes may be developed that enable the sensor to sensor variation to be maintained at an acceptably low level for the sensor performance upon reaching light-off, sensor to sensor variation may have a significant impact on sensor response during the light-off time. As a result, the sensor signal may not be usable until after light-off of the sensor has occurred.
The inventors herein have recognized the above problems and have devised various approaches to at least partially address them. Thus, in one example, a sensor is provided, the sensor comprising an output responsive to a sensed parameter; and a coded indication of a sensor light-off response for the sensed parameter. The sensor may be an exhaust gas sensor, such as an exhaust gas constituent sensor, and the coded indication of the sensor light-off response may include sensor-specific data particular to, and selected specifically for, the sensor. In this way, because the sensor provides a coded indication of its light-off response, systems using the sensor may be able to account for the manufacturing sensor to sensor variability in the sensed parameter. Therefore, the sensor may be used to accurately sense the sensed parameter even during the warm-up operation of the sensor, before reaching light-off. This can enable the sensor to be used for diagnosing engine and/or emission control system properties earlier in a vehicle drive cycle, for example, thus enabling improved vehicle diagnostics.
In another example, a method for decreasing the light-off time of a sensor is disclosed. The method comprises receiving sensed parameter data from the sensor, receiving encoded calibration data from the sensor, and adjusting a vehicle operating parameter in response to the sensed parameter data and the encoded calibration data. The encoded calibration data, which may correspond to a limited set of calibration codes indicating a sensor-specific light-off response for the sensed parameter, may be sent from the sensor to an engine control unit during the period after operation begins, but before the sensor reaches a stable light-off temperature. In this manner, the corresponding calibration data may be utilized to correct an otherwise degraded signal, thus reducing the amount of time to obtain usable output from the sensor.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.